Liquid fuse



April 9, 1935. R. H. EARLE Er AL LIQUID FUSE vFiled May 5, 1952 Patented Apr. 9, 1935 UNITED STATES, tPATENT iOFFICE LIQUID AFUSE Ralph H. Earle, Wauwatosa, and Walter E. Mittelstadt, Kenosha, Wis., assignors to Line Material Company, South Milwaukee, Wis.

Application May 5, 1932, SerialNo. 609,453

11 Claims.V (Cl. 200-120) This invention relates to lliquid fuses. shortened up) Showing the fllSe after it has In liquid fuses 'it 'is the customary 'practice Lto blOWn. provide'a tube 'of glass, "orotherinsulating ma- Figure 3 iS a SeCtiOnal VieWonthe line 3'3of terial, within whichan arc extinguishing liquid Figure 2.

f is carried. An upper and a lower Contact are Figure 4 is a fragmentary view of amodied 5 provided, connectedby'alfuse'linkand afleiible form of the invention. cable, a spring being'employed todraw thelower Referring to Figures l, 2 and 3 it will be seen portion ofthe fuse downwardly whenthe fuse that the fuse comprises an insulating'tube ll Of blOWS. These liquid ffuses frequently give conglass or other suitable material vprovidedwithia lo siderable trouble'due to the sudden evolution of lower contact2and an upper Contact?. rAfuSe l0 gaSeS producing a quickly applied gas pressure link of any suitable formindicated generallylby which, Under Short circuit or excessiveload oonthe reference character dis provided adjacent the ditions,'may break the glass tube. Another seriupper contact and is supported in any suitable ous defect of these devices is that when the fuse manner as by means of the toggle-Shaped Spring ie is ruptured, an -arc is established which fresupporting brdgemember 5 restingfn netehes l5 quently plays'about and damages the upper conformedin'a splitiferrule'or ring 1. .The ringlts tact, 'often cracking `and breaking the glass Within the upper portion of the upper contact vThis invention is designed 'to overcome the and-rests against the shouldered portion`8 formed above noted defects and objects of this lnventhereon. The toggle action of tile bridge'menl- 2o tion are to provide .a `novel 'form of liquid fuse ber 5 folCeS the endS of thebridge member against 20 which will prevent arcing 'to the'upper contact, the tWo halVeS 0f the Split ring i, Vandthll fOrCeS which greatly lengthens the path 'of 'the arc, the tWO haiVeS ofthe Split ring 7 downwardly which introduces a hairpin turn in'the path of androutwardly into 'lm Contact With the Upper the arc, which protects the glass Aor insulating contact 3, thereby securing an excellent electrical tube, which protects the Vupper contact, and connection betweenboth the halves of the split 25 which shoots the products cf'ccmbusticn faraway ring and the upper eontaet'i and between the from the 'fuse contacts. ring and the ends of the bridge member5 or the vIn greater detail, further objects 'are'to provide ends 0f the USe Wrapped thereon. a liquid fuse Vhaving a, ,msin'or stationary insu- The lower end'of the fuse link is detachably seso lating tube of glass cr other suitable material, Cured to a connect-01 or Clip 9 rmly attached t0 so and amovable insulating tube cf fiber cr other the upper end 0f a helical Spring I0 and to a insulating lmaterial which is initially housed flexible conducting Cable 0r leader I'L The lower within the glass 'tube and automatically moves end of the Spring IU and leader er cable 'Il are upwardly when the fuse b1cws and projects from Connected in any Suitable manner te the lower 35 the glass tube and from the upper contact, and 'Contact 2. If deSired, 'the intermediate DOItiOn 35 which thus substantially rinstantly greatly elcnef the fuse link may be covered by e cork 0r other gates the path which an are would have to follow similar member I 2 in a well known manner, and it and Vattire same time forms a Vent tube which iS also preferable, in aCCOI'danee With the Usual projects the products 0f Combustion far away construction, to provide a reduced portion (not 40 fromthe 'fuse contacts shown) `in the fuse link at that portion thereof 40 Further objects are to provide a construction CQVeredvby the Cork Iz- I y v which maybe applied to standard types of liquid The upper Contact is a rng'hk? member and fuses without alteration, which does not necessiis Closed by an easily rupturable diaPhlfagm '3 tate an increase in the overall dimensions ofthe we ferably'of sjome sofi 3110i' 0r of i smul ma" fuse, which is cheap 'and easy to produce, and trlal The dlaphrgm I3 1S hld m place b5.' a' 4D which is easy to re-fuse, the parts of the liquid ung nut .M and Whm the fuse 1S blown the dlafuse being protected against damage as heretophragm is torn mund lts edges and blown free f 1 d th n u th d t b from the ruse. It is preferable to provide a proore eXp ame my? Owing e evl O e tecting disc or shield I5 over the upper end of the used over land over again.

ringfnut I4 to thereby guard the diaphragm I3, 50 Embodlments of the invention are shown 1n the Such disc being provided with spring fingers I 6 accompanying drawing, in Whih clipped below the bottom edge 0f the ring nut I 4 Figure 1 is a vertical sectional view showing the vor held thereto in any other suitable manner. fuse in its-initial position. It is to be noted that the split ferrule 'I is pro- :Figure 2 'isa corresponding view (somewhat vided Withan inwardly projectingflower flange 'I'I 56 Y jected'upwardly into the position shown in Figure aninsulating tube i9 of ber or other suitable material. This ber tube is freely slidable upwardly through the ferrule l, or ring, and is pre- Y vented from dropping downwardly beyond its position shown in Figure l by means of an upper collar or upper shoulder 2G, preferably integrally formed thereon. Y

A second and lower shoulder 2l is formed at a point spaced downwardly from the upper shoulder 26, as clearly shown in Figures l and2, to limit the upward motion of the ber tube l. The ber tubehas an unobstructed central bore which provides a relatively large internal space within which the upper end of the spring lil and the major portion of the fuse link are positioned.

The-apparatus is filled with an arc extinguishing liquid to approximately the level indicated by the reference vcharacter 22. Such liquid is carbon tetrachloride or anyother suitable material.

It is to be noted that the split ring or ferrule l enables the ber tube to be formed as an integral structuregby merely reducing an intermediate portion thereof. The split ring is thereafter positioned about the ber tube and this structure is slipped into position within the main tube or fuse body. The operation of the device is wholly automatic and is as follows:

- When the `'fuse blows, the' outwardly rushing products Vvof combustion burst the rupturable diaphragm i3 and blow the central portion of the Y diaphragm, andthe disc i5 away from the fuse.

2. Any arc formed by the rupturing of the fuse cannot, therefore, pass to the upper contactA as it has first to pass through the projected ber tube I9 in the position shown in Figure 2, make a hairpin turn at the upper edge of the ber tube andloopbackwardly to the upper contact.

This construction, therefore, provided a relatively greatly increased length of travel for any are that can be vformed and in reality prevents the formation of such arc.

- it is to be noted at this point. that as the aberV tube moves upwardly, vthe supporting member 5 for the fuse slides upwardly still in contact with the metal ferrule 'l and any arc that is formed exists between the ruptured portions of the fuse link located within the ber tube. This entire structure' substantially instantly moves upwardly and thereby prevents the formation of an arc from the lower segment of the fuse link to the upper contact. Y f

In addition to the operation thus far described, the projected bertube shoots the products of combustion far away from the contacts of the fuse. VThese products of combustion include the highlyV heated gases which when at their ex- Y striking the glass tube, thus preventing the cracking of the glass tube.

The construction also provides for the immediate relief of the pressure gases and thereby protects the structure from rupture due to a sudden excessive rise in pressure. Instead of this a freely Y the inwardly projecting flange vented means is provided which also secures the above enumerated results.

Actualrtests of this apparatus have proven highly successful and it has been found that even under short circuit conditions that the fuse is highly reliable and produces remarkably good.

results. I p

Due to the fact that there is noburningot the upper contact and no cracking or breaking of the glass, it will be seen that the device can be used over and over again. Also, due to the simple construction and the unobstructed manner in which the apparatus is formed, re-fusing is which' is shown in Figure Ll. In this form of the invention the same construction is followed with the exception that the ber tube i9 is provided with a tapered portion 23 which wedges within il of the metal ferrule or split ring 'LY y It will be seen that theV device is very simple in construction, that it may be cheaply made, that it is applicable to standard types of fuse structures, and that it is reliable in operation.V

Although this invention has been described in considerable destail, it is to'be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpretedV as claimed.

We claim: i

l. A liquid fuse comprising a main tube including contacts at opposite ends andi adapted to contain an arc extinguishing liquid, a fuse link located whollyfwithin said main tube, a sleeve having a relatively large internal bore compared with the internal .bore of said Vmain tube, said sleeve being slidably carried wholly within said main tube and adapted to be projected outwardly therefrom whensaid fuse blows, said sleeve being normally spaced from both ends of said Ymain tube, and means for arresting the outward motion of said sleeve by an interlocking action betweenV said sleeve and said main tube. Y

2. A liquid fuse comprising a main tube adaptedlto contain an arc extinguishing liquid and having an annular upper contact and a'lower contact and having a closed lower end, a sleeve slidably mounted within said main tube and freely open at both ends and adapted to be projected outwardly through said annular contact when said fuse blows, said sleeve and said main tube having interlocking portions to limit the outward projection of said sleeve, said sleeve having a relativelylarge bore compared with that of the main tube and providing a relatively-,unobstructed passageway for the free discharge of gases, and a fuse link extending completely through said sleeve and located within said main tube and electrically connecting said contacts.

3; A fuse comprising a main tube having a contact closing one end thereof and having an annular-contact adjacent the Vother end thereof, a fuse link located within said-main tube and electricallygconnected to said contacts, and an insulating sleeve normally wholly housed within said main tube below the upper end of nular contactand projectable outwardly into a position protecting said annular Contact and projecting beyond the upper end of said annular Contact, said sleeve being freely open at both ends, said sleeve and said main tube having interlocking portions to arrest the outwardmotion of saidl sleeve after said sleeve has been projected a material distance outwardly from said main tube.

4. A fuse comprising a main tube having a contact closing one end thereof and having an annular contact adjacent the other end thereof, a conductor including a fuse link located within said main tube and electrically connected t said contacts, and an insulating sleeve normally housed within said main tube below the upper end of said annular Contact and projectable outwardly into a position protecting said annular contact and projecting beyond the upper end of said annular contact, said sleeve being a tube freely open at both ends and forming a conducting member for discharging gases above the upper end of said main tube'and at distance spaced therei rom after said fuse blows, said oonductor normally extending completely through said sleeve, over the upper end of said sleeve to said annular contact, said sleeve and said main tube having interlocking means to arrest the outward motion of said sleeve.

5. A liquid fuse comprising a main tube adapted to contain an arc extinguishing liquid, an upper annular contact .forming an extension of the upper end of said main tube, a lower contact closing the lower end of said main tube, conducting means electrically joining said contacts and located Within said main tube, said conducting means including a fusible section located adjacent said upper annular contact, and a sleeve of insulating material slidably positioned wholly within said main tube and projectable upwardly through said annular` upper contact, said sleeve having a relatively large bore with reference to the internal diameter of the main tube and being freely radially open at both ends, said sleeve and said main tube having interlocking means to arrest the outward motion of said sleeve, whereby said sleeve forms an extension of the main tube and conducts gases and spraying liquid away from said upper annular contact.

6. A liquid fuse comprising a main tube adapted to contain an arc extinguishing liquid, an upper annular contact forming an extension of the upper end of said main tube, a lower contact closing the lower end of said main tube, conducting means electrically joining said contacts and 1ocated Within said main tube, said conducting means including a fusible section located adjacent said upper annular contact, a sleeve of insulating material slidably positioned within said main tube and projectable upwardly through said annular` upper contact, said sleeve being freely open at both ends and forming a conducting extension for conducting gases and spraying liquid away from said upper contact, and means for arresting the upward motion of said sleeve with the upper end of said sleeve positioned above the upper annular contact.

'7. A liquid fuse comprising a main tube adapted to contain an arc extinguishing liquid, an upper annular contact adjacent the upper end of said main tube and forming an extension of the main tube, a lower contact adjacent the lower end of said main tube, conducting means electrically joining said contacts and located wholly within said main tube, said conducting means including a fusible section located adjacent said upper annular contact, a sleeve of insulating material slidably positioned within said main tube and having means for normally suspending said sleeve below the upper end of said annular contact, said sleeve being adapted to move outwardly when said fuse blows with a material portion of said sleeve projecting upwardly beyond the upper end of said annular Contact, said sleeve having a relatively large bore as compared with the diameter of the main tube and being freely open at both ends and forming an extension of said main tube foi` conducting discharged material therefrom when said fuse blows, and means for arresting the upward motion of said sleeve to determine its nal position.

8. A liquid fuse comprising a main tube, an annular contact adjacent the upper end of said main tube having an annular ilange, a slidable insulating tube having a reduced portion passing through said flange and having an enlarged lower portion for contacting with said annular ange to limit the outward motion of said sleeve upon blowing of said fuse, a lower contact carried by said main tube, and conducting means located within said main tube, electrically connecting said contacts, and passing through said sleeve.

9. A liquid fuse comprising a main tube an annular upper contact carrying an inwardly project-ing iiange located adjacent the upper end of said main tube, an insulating sleeve having a reduced portion passing through said annular flange and having an upper shoulder normally resting upon said flange, said sleeve being slidable outwardly through said flange, and having means for arresting the outward sliding motion when said sleeve projects beyond the upper end of said annular contact, and conducting means including a fuse link, said conducting means electrically joining said contact and passing through said sleeve.

10. A liquid fuse comprising a main tube, a lower contact closing the lower end of said main tube, an upper annular contact having a shoulder therein, a split ferrule resting upon said shoulder and having an inwardly projecting annular flange, an insulating tube slidably passing through said flange and having an upper shoulder normally resting upon said ilange, said tube being slidable through said ange to a position where it projects beyond the upper end of said annular contact, means for arresting the upward motion of said insulating tube to determine its final position after the fuse has operated, and a fuse link electrically connected to said contacts and located within said sleeve.

1l. A liquid fuse comprising a main tube, a lower contact closing the lower end of said main tube, an upper annular contact having a shoulder therein, a split ferrule resting upon said shoulder and having an inwardly projecting annular flange, an insulating tube slidably passing through said flange and having an upper shoulder normally resting upon said ange, said tube being slidable through said flange to a position where it projects beyond the upper end of said annular contact, means for arresting the upward motion of said insulating tube to determine its final position after the fuse has operated, a fuse link electrically connected to said contacts and located within said sleeve, and a rupturable diaphragm normally closing said annular upper contact and located above the upper end of said insulating tube.

RALPH H. EARLE. WALTER E. MITTELSTADT.

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